Summary: The last several years have seen an explosion in the manufacture and use of low-cost sensors for the measurement of air pollutants. Such sensors offer the promise of distributed measurements of atmospheric pollutants over wide geographical areas, and as such have important potential applications for source attribution, local air quality, and human health/exposure. However, it is critical that the performance (accuracy, precision, selectivity) of these sensors be well characterized, and continually monitored during measurement periods. In particular, as with all air quality instrumentation, sensors need to be regularly calibrated, which represents a major challenge for large-scale networks (with hundreds or even thousands of sensor nodes). General approaches include laboratory-based calibrations (exposing sensors to known levels of pollutants under controlled, well-defined conditions) and co-location calibrations (placing sensors near high-fidelity regulatory-grade monitors). However, neither approach has been demonstrated as effective on a large scale.
Project Goals: Development of novel approaches for the evaluation and calibration of low-cost sensors during and after deployment. NOAA is presently developing an air quality forecasting capability which would greatly benefit from an expanded base of observations. The development of novel approaches for the evaluation and calibration of low-cost sensors during and after deployment is critical to the implementation of a cost effective air quality observing network. Such approaches could be physical systems, such as portable calibration setups or calibration modules internal to the sensor nodes, or be methodology-based, such as new algorithms or descriptions of “best practices” for calibration. The approaches developed must be suited for large-scale use, be applicable to in-use sensors, and provide a means by which sensor performance (accuracy, precision, etc.) can be described quantitatively. Calibration approaches could be focused on a particular sensor or class of sensors (e.g., measurements of a single gas-phase pollutant, or of the number or mass concentration of particulate matter), or be broadly applicable to low-cost sensors generally